1) Field of the Invention
The present invention relates to a spatial light modulator and a projector, and more particularly, to a liquid-crystal spatial light modulator.
2) Description of the Related Art
A dot-matrix display device is widely used as an image display device, such as a liquid crystal panel (a liquid crystal display device), a cathode ray tube (CRT) display device, and a plasma display device. The dot-matrix display device displays an image by a number of pixels that are arranged periodically in two dimensional arrays. However, the periodic arrangement of the pixels causes a sampling noise that deteriorates quality of the image, which makes the image rough and less smooth. One of the methods to reduce deterioration of the quality of the image is disclosed in, for example, Japanese Patent Application Laid-Open No. H8-122709.
The dot-matrix image display device has a light-shielding portion called a black matrix. The black matrix is an area between each of the pixels to suppress an unnecessary light. In recent years, it is getting more popular to watch a large screen from comparatively close distance. For this reason, a watcher may recognize a black matrix image in a conventional dot-matrix image display device, resulting in the deterioration of the quality of the image. The conventional technology disclosed in the Japanese Patent Application Laid-Open No. H8-122709 can hardly reduce the deterioration of the quality of the image caused by the black matrix image.
One of the ideas to prevent the black matrix image from appearing is to input a light from the image display device into a prism group. Flat surfaces of the prism group transmit the light as it is; while refracting surfaces refracts the light. The light transmitted the prism group includes a straight light from the flat surfaces and a refracted light from the refracting surfaces. The refracted light is deflected and forms a pixel image on the black matrix area. As a result, the black matrix image becomes hard to recognize.
However, the characteristics of each prism element that composes the prism group sometimes cause a diffraction due to a variety of factors such as periodic arrangement, depth, arrangement pattern, arrangement pitch. A diffracted light from the prism group is dispersed and irradiated to undesired directions. The diffracted light makes the image blurred, resulting in the deterioration of the quality of the image. Furthermore, when the diffraction occurs in one region of the image display device and does not occur in other region, the displayed image becomes an image having an uneven light intensity in a lattice-pattern, a further deterioration of the quality of the image.
The present invention is made to solve the above problems. The object of the present invention is to provide a spatial light modulator and a projector that display a smooth image of a high-quality without having an image of the light shield portion such as the black matrix.